Process of assembling insulators



May 5 1936 J, J. TAYLOR 2,039,500

PROCESS OF ASSEMBLING INSULATORS Fild OCt. 26, 1934 ,J1 l ze@ INVENTOR Patented May 5, 1936 UNITED STATES PATENT OFFICE The Ohio Brass Com corporation of New pany, Mansfield, Ohio, a Jersey Application October 26, 1934, Serial No. 750,101

13 claims.

This invention relates to the manufacture of electric insulators formed of a plurality of parts, the materials ofwhich have different coefficients of expansion for temperature changes.

The invention has for one of its objects the manufacture of insulators in which the undesirablev effects of differential expansion and contraction, due to temperature changes, are largely eliminated.

A further object of the invention is to provide a method of assembling insulator parts which will automatically relieve the parts of the insulator that would otherwisev be subjected to stresses by differential expansion and contraction.

A further object of the invention is to provide insulator parts having bearing surfaces extending in the direction of relative movement caused by differential expansion or contraction and automatically relieving all other adjacent surfaces so that the only bearing surfaces will be those extending in the direction of relative expansion and contraction.

A further object of the invention is to provide a method of assembling insulators in which different parts are maintained at different temperatures during the assembly so that when the parts are all restored to the same temperature, certain adjacent surfaces will be relieved of contact.

A further object of the invention is to provide an improved process of manufacturing insulators and to produce a product which shall be of improved construction and operation.

Other objects and advantages will appear from the following description.

The invention is exemplified by the steps of the process described in the following specification and illustrated in the accompanying drawing.

In the drawing, the figure is a vertical sectional view of an insulator during assembly according to the present invention.

VVIn my prior application Serial No. 716,476, filed March 20, 1934, I have described and claimed an insulator formed of metal and porcelain or other dielectric material in which the bearing surfaces all radiate from a common point so that when differential expansion or contraction takes place, relative movement upon the bearing surfaces will be in the direction of these surfaces and not transverse thereto. All other adjacent surfaces of the connected parts in that application are described as being relieved so that bearing Will be confined to the surfaces arranged for relative movement without setting up stresses. The present invention provides means for conveniently and automatically accomplishing the relief of the desired surfaces during the process of assembly.

In the drawing the numeral I0 designates the hollow pin of a heavy pillar type insulator having a multipart dielectric member formed of shells II and I 2 and having a cap I3. Ihe shells I I and I2 are usually made of porcelain but the inven-l tion, of course, is not restricted to this particular material. The various parts are secured together by layers of cement I4, |5Vand I6. The cemented t surfaces of the porcelain are preferably provided with a treated sanded surface ofthe nature covered by Patents Nos. 1,284,975' and 1,360,352, granted respectively November 19, 1918 and November 30, 1920 to Arthur O. Austin.

The pin I 0 is provided with a plurality of bearing surfaces I 1, all of which radiate from a common internal point I8 so that relative movement between the pin andthe cement, due to differential expansion and contraction, will take place in the direction of these bearing surfaces, as more fully explained in my prior application referred to above.` The present invention automatically relieves all other surfaces contacting with the cement and so prevents bearing on said surfaces at working temperatures of the insulator so that the parts may expand and contract without pro 2 ducing stresses on these surfaces.

During assembly the plastic cement is introduced between the parts which areV then held in the arms I9 and 20 of a suitable jig in the usual manner. The pin I0 before assembly is preferably dipped in some material which will prevent thecement from being bonded to the pin. I find that a bituminous material commercially known as sarco is suitable for this purpose. The inner end of the pin is closed by a cement disc 2| to prevent the cement from entering the pin, and a fiber washer 22 may be placed in the bottom of the pin hole, as is common practice. Portland cement is commonly used for connecting the parts together, but other suitable materials which will harden when permitted to stand may be used. During the hardening of the cement, the pin I 0 is. heated to a higher temperature'than the surrounded parts so as to cause it to expand.

When the parts are restored to equal temperatures, the pin will then contract, which will cause the material of the pin to move inwardly along the bearing surfaces radiating from the point I8 and will draw all other surfaces of the pin away from the adjacent cement so as to relieve automatically all of the surfaces toward which the pin moves in expanding. `I t will be readily apparent that whenever the pin again expands relative to the surrounding material, the

surfaces will move toward the cement only where relief has been previously provided during the assembly of the insulator parts. Thus the proper surfaces to be relieved are automatically selected and all danger of failure to relieve the proper surfaces will be automatically avoided.

The differential heating of the parts may be accomplished in a number of ways. One method is illustrated in the drawing. In this method the interior of the. pin is partially filled with water or other heat conducting liquid, as indicated at 23. An electric heating element 24 is immersed in the water and current is permitted to flow through the heating element during the setting of the cement. The outer parts of the insulator are subject to an ambient temperature considerably lower than the temperature of the water. This insures a greater degree of relative expansion of the pin than would be provided simply by the difference in coeicients of expanspion between the pin and the dielectric member. It also prevents the cap from expanding to the degree that it would if the entire insulator were heated. The process of assembly maintains the pressure on the outside of the dielectric member so as to back up the porcelain during the expansion of the pin and during the time that the cement is setting.

During the hardening of the cement, the recesses 25 and 26 may be filled with water to supply the moisture taken up by the cement in hardening. The recess 21 may be packed with wet rags or other water absorbing materia1 for a similar purpose. While a convenient method of heating the pin is shown, it will be understood that any other suitable methods of heating may be employed without departing from the scope of the present invention, as dened in the appended claims.

I have found that in assembling an insulator similar to that shown in the drawing having a height of approximately 14 inches and a maximum diameter of approximately 20 inches, a 120 watt immersion heater will maintain a pin temperature of about 150 Fahrenheit, while the cap temperature will be maintained at about Fahrenheit when the ambient temperature is approximately '70 Fahrenheit. I have found it advisable to heat the water to about 170 Fahrenheit when it is first placed in the pin. After the cement has cured for about eighteen or twenty hours, the parts may be removed from the jig and curing completed under water at about Fahrenheit. The insulators` should remain in the curing bath for about seventy-two hours to give the best results.

I claim:

1. The method of connecting separate4 parts disposed one within the other comprising the steps of interposing plastic cement between the parts and maintaining the inner part at a higher temperature than the outer part during hardening of the cement.

2. In the manufacture of an insulator having an internal metal member, the steps of providing the metal member with bearing surfaces radiating from a common point, inserting said member within an opening in a dielectric member, introducing cement between said members and maintaining said metal member at a higher temperature than the surrounding ambient temperature during the hardening of said cement.

3. In the manufacture of an insulator having an internal pin, an external cap and an interposed dielectric member, the steps of introducing cement around the pin within the dielectric member and maintaining the pin at a higher temperature than the cap during the hardening of said cement.

4. In the manufacture of insulators having an internal pin, an external cap and an interposed dielectric member, the steps of forming the pin with bearing surfaces radiating from a common point, interposing cement around said pin within the dielectric member and maintaining the pin at a higher temperature than the temperature of said cap during the hardening of the cement.

5. The process of manufacturing an insulator comprising the steps of inserting a metal pin in a recess in a dielectric member, disposing cement around said pin within said recess, heating said pin and maintaining a lower ambient temperature about said insulator than the temperature produced within said pin during the hardening of said cement.

6. In the process of manufacturing an insulator having a pin, a cap and an interposed dielectric member, the steps of introducing the pin into an opening in the dielectric member, disposing the cap over the dielectric member, interposing cement between the pin and dielectric member and between the cap and dielectric member, heating the pin and maintaining a lower ambient temperature about the insulator than the temperature of said pin while said cement is hardening.

7. In the manufacture of insulators having a pin, a cap and an interposed dielectric member, the pin having oppositely tapered bearing surfaces radiating from a common point, the steps of introducing the pin into an opening in the dielectric member, placing the cap over a portion of the dielectric member about said pin, introducing cement between the pin and dielectric member and between the cap and dielectric member, preventing the cement from becoming bonded to the surface of the pin during the hardening of the cement, and maintaining a temperature difference between the pin and cap during hardening of the cement by heating the pin to a temperature above ambient temperature and at the same time exposing the cap to the ambient temperature.

8. In the manufacture of insulators composed of metal and dielectric members, the step of interposing plastic cement between said members, electrically heating one of said members during hardening of the cement, and maintaining an ambient temperature about the other member lower than that of the heated member during the hardening of the cement.

9. The method of assembling insulator parts comprising the step of introducing plastic cement between the parts, maintaining a heat conducting liquid in contact with one of said parts, and heating said liquid during the hardening of said cement, the ambient temperature about the other part being lower than the temperature of said liquid.

10. In the manufacture of insulators, the step of introducing a hollow pin into a recess in a dielectric member, interposing plastic cement between said pin and dielectric member, introducing a heat conducting liquid into said hollow pin, heating said liquid during the hardening of said cement and maintaining an ambient temperature about the dielectric member lower than the temperature of said liquid.

11. In the manufacture of insulators, each comprising a hollow metal pin having oppositely tapered bearing surfaces on the outer periphery thereof, said bearing surfaces tapering toward a,

common apex, the steps of introducing said pin into an opening in a dielectric member, interposing plastic cement in said opening about said pin and in contact with said tapering surfaces and with other non-bearing surfaces of said pin, introducing a heat conducting liquid into the interior of said hollow pin, heating said liquid and maintaining an ambient temperature about said insulator lower than the temperature of said liquid during the hardening of said cement.

12. The method of assembling an insulator comprising a dielectric member having a recess therein and a pin disposed in said recess, said pin having oppositely tapered bearing surfaces radiating from a common point and having a non-bearing surface between said bearing surfaces, said method comprising the steps of introducing cement within said recess about said pin, heating said pin and thereby expanding the same to cause the non-bearing surface between said bearing surfaces to press against said cement while said bearing surfaces move outwardly in the direction of their elements radiating from said common point so that when said pin is again contracted clearance will be provided between said cement and said non-bearing surface while said bearing surfaces will remain in contact with said cement.

13. The method of assembling insulators composed of parts, one of which has bearing surfaces radiating from a common point and non-bearing surfaces which do not radiate from said point, said method comprising the assembling of said parts with cement in contact with said bearing and non-bearing surfaces and heating said part and thereby expanding the same and causing said non-bearing surfaces to hold the cement in position during setting thereof to provide clearance between said cement and said non-bearing surfaces during normal operating temperatures of said insulator.

. JOHN J. TAYLOR. 

